ch13.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {
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   },
   "source": [
    "# Introduction to Modeling Libraries "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
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    "deletable": true,
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   "source": [
    "import numpy as np\n",
    "import pandas as pd\n",
    "np.random.seed(12345)\n",
    "import matplotlib.pyplot as plt\n",
    "plt.rc('figure', figsize=(10, 6))\n",
    "PREVIOUS_MAX_ROWS = pd.options.display.max_rows\n",
    "pd.options.display.max_rows = 20\n",
    "np.set_printoptions(precision=4, suppress=True)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "## Interfacing Between pandas and Model Code"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "import pandas as pd\n",
    "import numpy as np\n",
    "data = pd.DataFrame({\n",
    "    'x0': [1, 2, 3, 4, 5],\n",
    "    'x1': [0.01, -0.01, 0.25, -4.1, 0.],\n",
    "    'y': [-1.5, 0., 3.6, 1.3, -2.]})\n",
    "data\n",
    "data.columns\n",
    "data.values"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "df2 = pd.DataFrame(data.values, columns=['one', 'two', 'three'])\n",
    "df2"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "model_cols = ['x0', 'x1']\n",
    "data.loc[:, model_cols].values"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "data['category'] = pd.Categorical(['a', 'b', 'a', 'a', 'b'],\n",
    "                                  categories=['a', 'b'])\n",
    "data"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "dummies = pd.get_dummies(data.category, prefix='category')\n",
    "data_with_dummies = data.drop('category', axis=1).join(dummies)\n",
    "data_with_dummies"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "## Creating Model Descriptions with Patsy"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "y ~ x0 + x1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
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   "outputs": [],
   "source": [
    "data = pd.DataFrame({\n",
    "    'x0': [1, 2, 3, 4, 5],\n",
    "    'x1': [0.01, -0.01, 0.25, -4.1, 0.],\n",
    "    'y': [-1.5, 0., 3.6, 1.3, -2.]})\n",
    "data\n",
    "import patsy\n",
    "y, X = patsy.dmatrices('y ~ x0 + x1', data)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "y\n",
    "X"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "np.asarray(y)\n",
    "np.asarray(X)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "patsy.dmatrices('y ~ x0 + x1 + 0', data)[1]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "coef, resid, _, _ = np.linalg.lstsq(X, y)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "coef\n",
    "coef = pd.Series(coef.squeeze(), index=X.design_info.column_names)\n",
    "coef"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "### Data Transformations in Patsy Formulas"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "y, X = patsy.dmatrices('y ~ x0 + np.log(np.abs(x1) + 1)', data)\n",
    "X"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "y, X = patsy.dmatrices('y ~ standardize(x0) + center(x1)', data)\n",
    "X"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "new_data = pd.DataFrame({\n",
    "    'x0': [6, 7, 8, 9],\n",
    "    'x1': [3.1, -0.5, 0, 2.3],\n",
    "    'y': [1, 2, 3, 4]})\n",
    "new_X = patsy.build_design_matrices([X.design_info], new_data)\n",
    "new_X"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "y, X = patsy.dmatrices('y ~ I(x0 + x1)', data)\n",
    "X"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "### Categorical Data and Patsy"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
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   "outputs": [],
   "source": [
    "data = pd.DataFrame({\n",
    "    'key1': ['a', 'a', 'b', 'b', 'a', 'b', 'a', 'b'],\n",
    "    'key2': [0, 1, 0, 1, 0, 1, 0, 0],\n",
    "    'v1': [1, 2, 3, 4, 5, 6, 7, 8],\n",
    "    'v2': [-1, 0, 2.5, -0.5, 4.0, -1.2, 0.2, -1.7]\n",
    "})\n",
    "y, X = patsy.dmatrices('v2 ~ key1', data)\n",
    "X"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "y, X = patsy.dmatrices('v2 ~ key1 + 0', data)\n",
    "X"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "y, X = patsy.dmatrices('v2 ~ C(key2)', data)\n",
    "X"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "data['key2'] = data['key2'].map({0: 'zero', 1: 'one'})\n",
    "data\n",
    "y, X = patsy.dmatrices('v2 ~ key1 + key2', data)\n",
    "X\n",
    "y, X = patsy.dmatrices('v2 ~ key1 + key2 + key1:key2', data)\n",
    "X"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "## Introduction to statsmodels"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "### Estimating Linear Models"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "import statsmodels.api as sm\n",
    "import statsmodels.formula.api as smf"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "def dnorm(mean, variance, size=1):\n",
    "    if isinstance(size, int):\n",
    "        size = size,\n",
    "    return mean + np.sqrt(variance) * np.random.randn(*size)\n",
    "\n",
    "# For reproducibility\n",
    "np.random.seed(12345)\n",
    "\n",
    "N = 100\n",
    "X = np.c_[dnorm(0, 0.4, size=N),\n",
    "          dnorm(0, 0.6, size=N),\n",
    "          dnorm(0, 0.2, size=N)]\n",
    "eps = dnorm(0, 0.1, size=N)\n",
    "beta = [0.1, 0.3, 0.5]\n",
    "\n",
    "y = np.dot(X, beta) + eps"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "X[:5]\n",
    "y[:5]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "X_model = sm.add_constant(X)\n",
    "X_model[:5]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "model = sm.OLS(y, X)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "results = model.fit()\n",
    "results.params"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "print(results.summary())"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "data = pd.DataFrame(X, columns=['col0', 'col1', 'col2'])\n",
    "data['y'] = y\n",
    "data[:5]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "results = smf.ols('y ~ col0 + col1 + col2', data=data).fit()\n",
    "results.params\n",
    "results.tvalues"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "results.predict(data[:5])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "### Estimating Time Series Processes"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "init_x = 4\n",
    "\n",
    "import random\n",
    "values = [init_x, init_x]\n",
    "N = 1000\n",
    "\n",
    "b0 = 0.8\n",
    "b1 = -0.4\n",
    "noise = dnorm(0, 0.1, N)\n",
    "for i in range(N):\n",
    "    new_x = values[-1] * b0 + values[-2] * b1 + noise[i]\n",
    "    values.append(new_x)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "MAXLAGS = 5\n",
    "model = sm.tsa.AR(values)\n",
    "results = model.fit(MAXLAGS)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "results.params"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "## Introduction to scikit-learn"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "train = pd.read_csv('datasets/titanic/train.csv')\n",
    "test = pd.read_csv('datasets/titanic/test.csv')\n",
    "train[:4]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "train.isnull().sum()\n",
    "test.isnull().sum()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "impute_value = train['Age'].median()\n",
    "train['Age'] = train['Age'].fillna(impute_value)\n",
    "test['Age'] = test['Age'].fillna(impute_value)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "train['IsFemale'] = (train['Sex'] == 'female').astype(int)\n",
    "test['IsFemale'] = (test['Sex'] == 'female').astype(int)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "predictors = ['Pclass', 'IsFemale', 'Age']\n",
    "X_train = train[predictors].values\n",
    "X_test = test[predictors].values\n",
    "y_train = train['Survived'].values\n",
    "X_train[:5]\n",
    "y_train[:5]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "from sklearn.linear_model import LogisticRegression\n",
    "model = LogisticRegression()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "model.fit(X_train, y_train)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "y_predict = model.predict(X_test)\n",
    "y_predict[:10]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "(y_true == y_predict).mean()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "from sklearn.linear_model import LogisticRegressionCV\n",
    "model_cv = LogisticRegressionCV(10)\n",
    "model_cv.fit(X_train, y_train)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "from sklearn.model_selection import cross_val_score\n",
    "model = LogisticRegression(C=10)\n",
    "scores = cross_val_score(model, X_train, y_train, cv=4)\n",
    "scores"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "deletable": true,
    "editable": true
   },
   "source": [
    "## Continuing Your Education"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "deletable": true,
    "editable": true
   },
   "outputs": [],
   "source": [
    "pd.options.display.max_rows = PREVIOUS_MAX_ROWS"
   ]
  }
 ],
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